Ok, I didn't know Holloway was up for Crossbones. I just remember him and the guy from Game of Thrones were mentioned, and it might or might not have been for a villain role. I'm a bit out of the loop.

It was never said who Holloway or Waldau were specifically being cast for. Some people are just assuming that, since we haven't heard anything more from those rumors after Grillo was officially cast, that one or both of them might've been in the running for Crossbones, too.